After eight gasp-filled seasons of “Desperate Housewives,” the sun finally sets on Wisteria Lane as the comedy/drama/mystery series reaches its two-hour finale Sunday at 9 p.m. on Channel 5. And though we must say our goodbyes to Bree, Lynette, Gaby, and Susan, the trusty TV formula that brought them together isn’t going anywhere. “Desperate Housewives” is part of a proud TV lineage of fearsome female foursomes — from “The Golden Girls” right up to “Girls.” At the heart of the formula’s success is a precision-crafted dynamic that keeps the characters hugging, fighting, and talking it out, while viewers toggle their empathies between archetypes that never wear out.